COMBUSTION ENGINES CLASSIFICATION

COMBUSTION ENGINES CLASSIFICATION

1. Internal combustion engines

   • Piston engines
     • Fossil fuel combustion is produced inside the engine and the explosion achieved, and gases that appear, are used to move a piston with a lineal and repetitive up-and-down or back-and-forward motion.
       • A four-stroke engine completes the thermodynamic cycle in four movements of the piston (between the moment in which petrol come inside the cylinder and it is repeated this action, piston has four movements); for this reason is called four-stroke engine. Use petrol as a combustible. Used in the most of the petrol cars.
         • The two-stroke engines follow the Otto thermodynamic cycle as well, but this engine complete the cycle in two movements of the piston; for this reason is called two-stroke engine. Two-stroke engines require a specific oil to gas ratio. It is used in some motorbikes.
   • Rotary engines
     • Rotary engines are internal combustion engines in which the combustion generates directly a rotary movement. It is not necessary the use of pistons. In these engines, the crankshaft remained stationary and the entire cylinder block rotated around it.
     • Wankel engine.
       • This engine uses a rotary design to convert pressure into a rotating movement. The engine follows the thermodynamic Otto cycle, so that, it is possible to say that Wankel engine is a four-stroke engine as well.
     • Gas turbines and jet engines
       • Gas turbines are rotary engines that extract energy from a flow of combustion gas. In the combustion, the hot gases produced are forced into the turbine to move its blades and so, it is possible to generate electricity in electric power stations. Jet engines are used in different machines such as the aircrafts. Jet engines create force by releasing a high speed jet of a liquid or a gas, pushing the plane through the air.

2. External combustion engines

   • Steam engines
     • In a chamber outside the engine called the boiler (or furnace), fossil fuels were burned to boil water, resulting in the production of steam. Since steam takes up to 1,500 times more space than water, the pressure generated could be used to move a piston, transforming heat energy into mechanical energy (movement).
   • Steam turbines
     • Steam turbines transform pressurized steam, turning its blades in a rotation movement This rotation movement is generally used to generate electricity. It is used in electric power stations.